feat: add debian packaging, CI/CD and update script

- Add debian/ packaging for .deb generation
- Add .forgejo/workflows/build.yml for CI/CD (runner label: docker)
- Add scripts/fullupdater and scripts/fullupdater-update
- Remove obsolete install.sh
- Update .gitignore for debian build artifacts

scripts/fullupdater

@@ -0,0 +1,14 @@
+#!/bin/bash
+set -e
+
+# Wrapper script installed at /usr/local/bin/fullupdater
+SCRIPT_DIR="/opt/full-updater"
+VENV_DIR="$SCRIPT_DIR/.venv"
+
+if [ ! -d "$VENV_DIR" ]; then
+    echo "Erreur : le venv n'existe pas. Réinstallez le paquet full-updater."
+    exit 1
+fi
+
+source "$VENV_DIR/bin/activate"
+python3 -m full_updater "$@"